Study: liquid biopsy is effective to analyze tumors

Biopsies from blood samples may be as effective as traditional tumor biopsies, said researchers at the American Society of Clinical Oncology (ASCO) on Saturday. This new method would be a great “minimally-invasive” alternative for patients who cannot undergo a tissue biopsy.

Researchers explained that having a new method for detecting cancer beyond tumor biopsy, would help physicians to select better treatment for patients, based on their needs. Detailed findings were presented on Saturday at the 2016 ASCO Annual Meeting.

Sumant Kumar, ASCO expert in developmental therapeutics, said that genomic mutations may vary and change over time among patients. This may be a major challenge for cancer treatment in the “precision medicine era,” Kumar added.

Patient Carole Linderman has her blood drawn for a liquid biopsy at Jefferson University Hospital in Philadelphia. Image courtesy of AP Photo/Jacqueline Larma.

The study considered patterns of genetic changes in blood samples and compared them to those in tumor biopsy. Researchers analyzed blood samples from more than 15,000 patients with 50 different tumor types.

Authors said that this was the largest cancer genomic study every conducted. Physicians traditionally depend on tumor biopsies, to determine if tumors have genetic mutations that can be treated using cancer drugs.

“The liquid biopsy provides an unparalleled opportunity to monitor changes in the disease as it evolves over time.”

A tumor biopsy is a surgical procedure that may be harmful to some patients, who do not meet the necessary health conditions. Philip Mack, Professor at the University of California Davis Comprehensive Cancer Center, said that monitoring tumors can sometimes be complicated.

“These findings suggest that analysis of shed tumor DNA in patient blood, also known as a liquid biopsy, can be a highly informative, minimally-invasive alternative when a tissue biopsy is insufficient for genotyping or cannot be obtained safely,”

Professor Mack added that liquid biopsy, also known as “Guardant360,” brings a great opportunity for patients and physicians who want to understand how a tumor changes over time. The study explains that DNA from tumor cells can be found in the bloodstream.

Traces of genetic material from tumors can be obtained from the blood and then analyzed into a lab. Results would help health providers to make “informed treatment decisions”. Liquid biopsies can also be conducted to monitor disease progression.

Study details and other theories: Periodic liquid biopsy may be preferable than tissue biopsy

Researchers analyzed data obtained from 15,191 patients, of which 37 percent had lung cancer, 14 percent breast cancer, 10 percent colorectal cancer and 39 percent other types of cancer. All participants provided a blood sample to be studied for ctDNA.

The study wanted to determine if liquid biopsies were equally accurate than tissue biopsies. Authors analyzed patterns of genomic changes in ctDNA of patients, and “consistency in the frequencies of specific changes in ctDNA”.

Findings concluded that liquid biopsies are accurate to show the “genomic landscape of the tumor,” said study authors in a press release issued Saturday by the ASCO. Results demonstrate that the new method is also effective at detecting genomic alterations linked to resistance to cancer drugs.

Is liquid biopsy the positive alternative to tissue biopsy?

After analyzing genetic changes of tumors, based on liquid biopsy, researchers suggested a list of possible treatment methods to physicians of participants. It included drugs approved by the U.S. Food & Drug Administration and clinical trials.

In general, ctDNA testing suggested treatments for almost two-thirds of patients (63.6 percent). The test has been especially useful for participants with lung cancer, whose tissues were insufficient for tissue biopsy.

“Among these cases, the ctDNA test identified key genetic mutations at frequencies consistent with their prevalence in the published literature, providing these patients with their only source of an actionable target.” said researchers in a press release, referring to lung cancer patients.

Authors concluded that liquid biopsies can be ideal for continuously monitoring the disease progression, response to treatment and development of resistance to some treatments. For instance, continuous monitoring can help physicians to adjust treatment plans.

A theory proposes that genetic changes in ctDNA take place even before tumor manifest and grow. A liquid biopsy would also help doctors to prove better treatments in less time. This procedure only requires a blood sample.

On the other hand, tissue biopsy needs small pieces of tumors. This technique can lose some “key mutations”, depending on the different part of the tumors, said the study authors in a statement.

Number of cancer survivors in the United States are expected to increase by 2026

The American Cancer Society and the National Cancer Institute said on Tuesday that there are 15.5 million cancer survivors in the country as of 2016. That number is expected to grow to 20 million by 2026.

The three most common cancer types among male survivors include prostate cancer, colon and rectal cancer, and melanoma skin cancer. On the other hand, most female survivors previously had breast cancer, uterine cancer and colon and rectal cancer.

New findings showed that 47 percent of all cancer survivors are over the age of 70, being 65 the median age of diagnosis.